Wellhead re-entry apparatus



May 26, c P. TE ETAL WELLHEAD RE- ENTRY APPARATUS Filed July 31, 1968 2 Sheets-Sheet 1 M l5 F I3: jls I I as 27 :1 3o r- L 29 a 1 i i; l 46 h 42 4| I 43 FIG. 5

30 r E o 36 1 5 37 E} 45 i 26 1 4e 44 25 INVENTORS: c. P. PETERMAN THEIR ATTORNEY May 26, 1970 C. P. PETERMAN EI'AL WELLHEAD RE- ENTRY APPARATUS Filed July 51, 1968 FIG. 2

2 Sheets-Sheet 2 NIH FIG. 3

INVENTORS C. P. PETERMAN P. L. DODD THEIR ATTORNEY United States Patent US. Cl. 166.5 Claims ABSTRACT OF THE DISCLOSURE Apparatus lowerable from a floating vessel onto an underwater Wellhead structure, the apparatus being operative to (1) attach a mono-guideline to the structure and (2) remove a wellhead closure means from the structure.

This invention relates to apparatus for use in carrying out operations with respect to underwater wells at deep water locations from a floating vessel.

More particularly, the present invention comprises apparatus lowerable by means of a pipe string from a floating vessel to an underwater wellhead structure including wellhead closure means and mono-post means, the apparatus being cooperable with said structure to attach mono-guideline means to said mono-post means and remove said wellhead closure means from the remainder of said wellhead structure upon suitable manipulation of the apparatus from the vessel by means of the pipe string.

During recent years, the continued search for oil has resulted in developing methods and apparatus for drilling underwater wells at locations where the water may range from 100 to 1,500 feet or more in depth. In these locations it has become the widespread practice to position a wellhead at a considerable distance below the surface of the water, preferably on the ocean floor, so that it is not a hazard to navigation of ships in the area.

One method of drilling and completing an underwater well on the ocean floor is described in US. Pat. No. 3,256,937, issued to J. A. Haeber et al., on June 21, 1966. In the method described in that patent a wellhead assembly is permanently positioned on an underwater wellhead and a series of guidelines extend from the wellhead assembly to a drilling barge or other drilling vessel floating on the surface of the water. Through the use of the guidelines various pieces of equipment are raised and lowered between the wellhead assembly and the vessel. After well drilling operations have been completed, the guide cables are left permanently attached to the wellhead assembly at their lower ends and are secured, preferably to a buoy, at their upper ends, with the buoy floating on the surface of the Water. Alternatively, the cables are dropped to the ocean floor from which they are subsequently recovered by means of grappling hooks or other suitable means. Since cables lying on the ocean floor tend to become entangled with each other and with the wellhead assembly and since guide cables attached to a floating buoy also have a tendency to become entangled as well as to constitute a hazard to sea traflic, it is desired that these guide cables be removed when drilling operations have been completed.

For this reason it has been found desirable to provide methods for establishing contact with an underwater well or other underwater installation and installing guidelines between the installation on the ocean floor and a vessel on the surface of the water by remote means. One such method is described in copending US. application Ser. No. 749,195, filed July 31, 1968, wherein a monoguideline is attached to an underwater installation by remote means, the mono-guideline subsequently being utilized to guide multiple guidelines or cable attaching means into operative engagement with the underwater installation.

It is a common practice whenever operations with respect to an underwater wellhead assembly are abandoned temporarily to provide closure means on the assembly entry conduit whereby the interior of the assembly is protected from the possible harmful effects of the sea water. Removal of the closure means must of course be accomplished prior to placing equipment on the entry conduit and in operative communication with the interior of the assembly.

SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide apparatus whereby contact may be established with an underwater wellhead assembly or other underwater installation through the remote connection of a mono-guideline between a floating vessel and the underwater installation.

A further object of the present invention is to provide apparatus lowerable from a floating vessel onto a wellhead structure, the apparatus being operative to (1) attach a mono-guideline to the structure and (2) remove a wellhead closure means from the structure.

These objects have been attained in the present invention by providing apparatus lowerable from a floating vessel onto a wellhead structure positioned underwater, such apparatus being effective to attach a mono-guideline to the structure and, in addition, remove from the structure a well head closure device associated therewith. The apparatus includes a housing means lowerable from the vessel by means of a pipe string having associated therewith a support fixture releasably engaging a latch element on the mono-guideline. Upon initial engagement between the apparatus and the structure, the latch element is attached to a monopost associated with the structure. Further downward movement of the apparatus brings the housing into locking engagement with the wellhead closure device. Upon upward movement of the apparatus, the closure device is removed from the structure and the mono-guideline remains attached to the structure.

DESCRIPTION OF THE DRAWING These and other objects of the invention will be understood from the following description taken with reference to the drawing, wherein:

FIG. 1 is a diagrammatic view taken on longitudinal projection illustrating a floating platform positioned on the surface of a body of water having associated therewith apparatus according to the present invention;

FIGS. 2 and 3 are enlarged longitudinal views in partial cross section showing details of selected portions of the present invention;

FIG. 4 is an enlarged isometric view illustrating cooperating elements according to the present invention; and

FIGS. 5 and 6 are views taken on longitudinal projection illustrating the relative positions assumed by elements of the present invention during selected stages in the operation thereof.

Referring to FIG. 1 of the drawing, a floating workover platform or barge 11, of any suitable floatable type is illustrated as floating on the surface of a body of water 12 and substantially fixedly positioned over a preselected drilling location by suitable barge positioning means or by being anchored to the sea bed (not shown) by suitable anchors (also not shown) connected to anchor lines 13 and 14 in the usual manner. Equipment of this type may be used when carrying out underwater well workover operations in water depths varying from about to 15 00 feet or more. The workover barge 11 is equipped with a suitable derrick 15 as well as other auxiliary equipment needed for operations of this type. The derrick 15 is positioned over a slot or well 16 which extends vertically through the vessel in a conventional manner. When using the equipment of the present invention the slot of barge 11 may be either centrally located or extend in from one edge. However, operations may be carried out over the side of the barge or vessel without the use of a slot. Additionally, it is to be understood that the equipment of the present invention also may be used when performing operations with respect to a well from any suitable operational base positioned above the surface of the water, such for example, as from a barge having feet extending to the ocean floor or from a platform permanently positioned on the ocean floor.

An underwater wellhead structure 17 is located on the sea bed (not shown) below vessel '11. It is to be assumed that the vessel has been positioned and anchored as illustrated through the use of conventional navigational aids. The lower portion of the wellhead structure has not been illustrated for purposes of simplicity and since that portion of the structure forms no part of the present invention. It is to be assumed, however, that the portion not shown is of conventional design and is secured in the usual manner to a well casing (also not illustrated) which extends down into the well, with upstanding conduit member 18 communicating with the interior of the well. When the wellhead structure is in operation, the interior of conduit member 18 is normally protected from the possible harmful effects of the sea water by closure member 19, which may be releasably secured to the end of the conduit in the manner illustrated by suitable attachment means such as spring-detent means (not shown). Closure member 19 includes a grasping element 20, the purpose of which will be more fully disclosed below.

A support bracket 21 extends laterally fromconduit member 18 and has fixedly secured thereto an upstanding mono-post or guidepost 22. A substantially V-shaped groove or slot 23 is provided on the side of guidepost 22, defining opposed sloping shoulders 24 and 25. The guidepost terminates at its upper end with a male coupling member 26. The operation of the groove 23 and male coupling member 26 will be described in detail below.

When carrying out operations, such as workover operations, through use of the subject invention, a pipe string 27 is lowered fromvessel 11 as illustrated in FIG. 1. The lowering operation is performed in the customary manner, i.e. through the lengthening of the string by the addition of individual pipe sections thereto. Attached to the lower end of pipe string 27 is a cylindrical housing member 28. The housing member 28 has been fixedly secured previously to the initial section of the pipe string lowerable from vessel 11 in any desired manner such as by use of screw threads. Attached to the lower end of the housing member by bracket member 29 is a cylindrical support element 30.

As shown in FIG. 2, cylindrical support element 30 has disposed therein an open ended tubular member 31 which has an elongated channel or groove 32 formed in the outer wall thereof. The outer diameter of tubular member 31 is slightly less than the inner diameter of support element 30 so that the tubular member may freely move longitudinally with respect to said support element. A key member 33 is fixedly positioned with respect to support element 30 and extends inwardly of the support element inner wall to cooperate with channel 32. With this arrangement, tubular member 31 is prevented from rotating relative to support element 30 but may move longitudinally with respect thereto a distance equal to that between abutment members 34 and 35 defining the ends of channel 32. The tubular member 31 is of relatively thick-walled construction at the upper portion thereof (as viewed in FIG. 2) but the tubualr member wall is of reduced thickness at its lower end thereby defining annular shoulder member 36. The

lower portion of tubular member 31 is adapted to accommodate a latching member 37 which may be of any suitable construction such as that disclosed in US. Pat. No. 3,050,140, issued Aug. 21, 1962, to W. J. Hayes. The external dimensions of the latching member 37 are less than the inner wall dimensions of tubular member 31 so that the latching member is freely movable therein for both rotatable and linear movement. A mono-guideline 3-8 is attached to latching member 37 and extends upwardly to a constant tension hoist 39 (FIG. 1) on vessel 11 which serves to retain the upper portion of the latching member in engagement with shoulder member 36.

With continued reference to FIG. 1, cylindrical housing member 28 also has attached thereto by means of a suitable frame or brace member 40 well locating means such as sonar unit 41 and television camera 42. The sonar unit 41 and television camera 42 may be of any known watertight construction and are operatively connected to suitable cable means 43 which extends upwardly along pipe string 27 to vessel 11 whereby the operation of the sonar unit and the television camera may be monitored by an operator on board the vessel. Cylindrical housing member 28 carries at its lower end a plurality of locking members 44 which extend into the interior of the housing member in the manner shown and are biased in this inward direction by any desired expedient such as spring means 45. Hydraulic biasing means could, of course, also be used for this purpose.

The operation of the present invention will not be described. As stated above, vessel 11 is psoitioned substantially over underwater wellhead structure 17 through the use of conventional navigational aids and anchored. Cylindrical housing member 28, as well as the equipment depending therefrom, is then lowered from the vessel by means of pipe string 27. This lowering operation is carried out in the uusal fashion, i.e. through the addition of individual pipe sections to the string. After it has been determined that the pipe string has been lowered to such an extent that the housing 28 and equipment depending therefrom are positioned above the sea bed at a distance slightly greater than the height of the wellhead structure 17, the sonar unit 41 and television camera 42 are actuated and monitored from the vessel.

Through the use of these last mentioned well locating means, the pipe string may be manipulated from the vessel until support element 30 is positioned over and in axial alignment with guidepost 22. The pipe string is then lowered to stab latching member 37 onto the guidepost. Preferably, a cone-shaped flange 46 depends from the lower end of said support element 30 to assist in the proper positioning of said support element and said latching member with respect to the guidepost. The cone-shaped flange has a cut-out portion 47 to enable television camera 42 to have a clear line of view with respect to the stabbing operation.

As stated above, mono-guideline 38, as it is lowered along with support element 30, is maintained under constant tension by hoist 39 on vessel 11. In this manner, the upper portion of latching member 37 is held in engagement with shoulder member 36 in the course of downward movement. For purposes which will be brought out more fully below, it is necessary to provide some means for retaining abutment member 34 (FIG. 2) of tubular member 31 in contact with key member 33, i.e. maintain tubular member 31 in a telescoped position within support element 30 as shown in FIG. 1, during the lowering of the pipe string 27 despite the constant upward pressure exerted on the tubular member 31 by means of latching member 37 and mono-guideline 38. One means for accomplishing this end is illustrated in FIG. 3 of the drawing wherein cooperating portions of tubular member 31 and support element 30 are shown in the respective positions assumed thereby during the above-described lowering operation. It may be seen that the tubular member 31 is held against upward movement with respect to support element 30 by means of a retaining device including an outwardly biased ball member 48 cooperating with an indent 49 on the inner wall of the support element. The ball member is biased by compression spring 50 housed in tubular member 31 in any desired manner. The compressive force exerted by spring 50 upon ball member 48 will be sufiicient to prevent tubular member 31 from being pulled outwardly of support element 30 by the substantially constant upward pressure being exerted on latching member 37 by hoist 39. It should be pointed out that the ball member and indent arrangement shown is merely illustrative of one possible retaining means that might be used for this purpose. For example, hydraulically or electrically operated latch means might be utilized with equal facility.

The operation of stabbing downwardly with the pipe string accomplishes a first result of latching to guidepost 22 the latching member 37. Continued downward movement of the string forces disengagement of ball member 48 from indent 49 thereby permitting tubular member 31 to move upwardly and outwardly with respect to support element 30 in the manner shown in FIG. 2. Simultaneously with the upward and outward movement of tubular member 31 with respect to support element 30, an inwardly extending protrusion 51 (FIGS. 2 and 4) fixedly mounted on the lower end of support element 30 enters into groove 23 on guidepost 22. If desired, the support element may include an additional oppositely disposed protrusion 51 which cooperates with a groove 23 on the other side of guide post 20. In the event the stabbing operation is made with housing 28 not axially aligned with conduit member 18, protrusion 51 engages either shoulder 24 or 25 to pivot tubular member 31, support element 30 and housing 28 about guidepost 22 to effect axial alignment between housing 28 and conduit 18 during the course of the continued lowering of pipe string 27.

The final phase of the lowering operation is reached when axial alignment between housing 28 and conduit 18 has been reached and the housing is lowered over closure member 19 thereby snapping locking members 44 under the outstanding portions of grasping element 20. The lowering operation is terminated when the elements of the present invention are in the positions illustrated in FIG. 5. At this point, latching member 37 has been attached to guidepost 22 and grasping element of closure member 19 has been engaged by locking members 44.

Suitable operations are now performed on board vessel 11 to retrieve the pipe string 27 and the equipment depending therefrom. Upward movement of the string moves closure member 19 from conduit 18 while support element 30 and tubular member 31 are pulled free of guidepost 22 and latching member 37, with the latching member remaining attached to the giudepost as shown in FIG. 6. Conduit 18 is now exposed so that the appropriate equipment may be lowered down mono-guideline 38 and placed in operative engagement with the conduit whereby communication may be established with the interior of the well for purposes of performing the desired operations.

We claim as our invention:

1. Apparatus for carrying out operations at a well site installation on the floor of a body of water from a floating vessel on the surface of the water, said apparatus comprising:

a pipe string depending from said vessel;

housing means mounted on the lower end of said pipe string;

mono-guideline means depending from the vessel with latching means operatively associated therewith;

support means mounted on the lower end of the housing means and releasably engageable by said latching means;

a wellhead structure positioned above and operatively associated with the well and having wellhead closure means;

upstanding guidepost means fixedly positioned with respect to said wellhead structure; and

latch actuation means responsive to the lowering of said support means onto said guidepost means by said pipe string to latch said latching means onto said guidepost means;

the housing means being responsive to further movement of said pipe string after said latching means has been latched to said guidepost means to remove said wellhead closure means from said wellhead structure.

2. The apparatus according to claim 1 including welllocating means operatively associated with said pipe string to assist the operator in positioning the pipe string with respect to said wellhead structure, said well-locating means comprising a sonar unit and television camera carried by a frame on said pipe string.

3. The apparatus according to claim 1 including a coneshaped flange depending from the lower end of said support means to assist in the proper positioning of said support means with respect to said guidepost means.

4. The apparatus according to claim 1 including cooperating orienting means provided on said guidepost means and said housing means to properly orient said housing means with respect to said wellhead closure means.

5. The apparatus according to claim 1 wherein said wellhead closure means is releasably attached to said wellhead structure and includes a grasping element adapted to be engaged by locking means on said housing means whereby the closure means may be removed from the wellhead structure.

References Cited UNITED STATES PATENTS 3,050,140 8/ 1962 Hayes 166.6 X 3,166,123 1/ 1965 Watkins 166-.6 3,302,709 2/1967 Postlewaite 166.6

NILE C. BYERS, SR., Primary Examiner R. E. FARREAU, Assistant Examiner US. Cl. X.R. -7 

